[Need help to find a movie title....please.]

Thank you very much, Jack. I had read the description for Laura but didn't realize that was the correct movie. Thanks again!!!

[Need help to find a movie title....please.]

A young woman who is new in advertising gets a big name to sign w/ her company. She approaches him while he is out to lunch alone. He first turns her down and then shows up at the ad agency to sign with the company. I thought the man was Clifton Webb but can't find anything with him in it like this. The man takes her under his wing. Eventually she is at a cabin to get away from the city and she is thought to be murdered. Her fiance is a suspect accused by the (Clifton Webb) character. She then returns and the guy whom I thought was Clifton Webb tries to murder her. Oh, and there is a large grandfather clock that has an opening at the bottom that is important at the end of the movie. I know this is pretty vague. There is more to the movie of course, I am just not good at explaining. If anyone has a clue to this movie....please, please let me know. Thank you for your time.! Its much appreciated.